So far, so good. I tried this, though, and although my people gallery was populated, none of the photos they contained could be found. I guess this is because the links in the meta data pointed to non-existent folders. So, step 2

Add a link to recreate the drives to match your windows ones. On mine, I had photos on E:\photos, mounted on Ubuntu as /media/data

$ cd ~/.google/picasa/3.0/dosdevices$ ln -s /media/data 'e:'

This should then mean the existing Picasa meta data points to an existent path. Make sure that you re-import your photos using the new mapped drive though.